Here is an article about the 1998 California proposition which limited bilingual education. It reports that the shift to English immersion has been quite beneficial for Hispanic students which is consistent with other accounts that I have read. Apparently, whatever the theoretical merits of bilingual education, as actually practiced in the United States it is actively harmful. This seems to be fairly well established. Still many liberals continue to reflexively support bilingual education in other parts of the country. Strange and ironic how separate and unequal classes have become politically correct.